The present invention relates to data storage medium, such as disks and disk cartridges, for storing digital information. Particularly, this invention relates to an apparatus and method of lifting read/write heads of a disk drive on to and off of a surface of a data storage medium within the disk drive. More particularly, the invention relates to a roll-stabilized head lifter device with a sliding shelf to minimize roll during the loading and unloading of the read/write heads onto the data storage medium of a disk.
Removable disk cartridges for storing digital electronic information typically comprise an outer casing or shell that houses a disk-shaped magnetic, magneto-optical, or optical storage medium upon which information can be stored. The cartridge shell often comprises upper and lower halves that are joined together to house the disk. The disk is mounted on a hub that rotates freely within the cartridge. When the cartridge is inserted into a disk drive, a spindle motor in the drive engages the disk hub in order to rotate the disk within the cartridge at a given speed. The outer shell of the cartridge typically has an opening near one edge to provide the recording heads of the drive with access to the disk. A shutter or door mechanism is often provided to cover the head access opening when the cartridge is not in use to prevent dust or other contaminants from entering the cartridge and settling on the recording surface of the disk.
Disk drives for use with such removable disk cartridges or cartridgeless disks typically employ either a linear actuator mechanism or a radial arm actuator mechanism for positioning the read/write head(s) of the disk drive on the recording surface(s) of the storage medium, or disk. Because the disks are designed to be removable from the drive, the linear or radial arm actuators must be able to move off, and away from, the storage medium to a retracted position in order to prevent damage to the head(s) when a disk is inserted or removed from the disk drive.
Many removable disk drives employ a pair of opposing read/write heads for recording and reproducing information on both sides of a storage medium. Typically, the opposing heads are disposed on flexible suspension arms at the distal end of an actuator that allow the heads to fly closely over the respective surfaces of the rotating disk. The opposing heads must be spread apart as they approach the edge of the disk during a head loading operation in order to avoid collision with the edge of the disk. Similarly, when the heads are unloaded from the disk, they must again be spread apart to avoid collision with the edge of the disk and each other.
One type of mechanism for controlling the loading and unloading of heads in connection with a linear actuator mechanism is through the use of wings that are attached to the heads and that act to control the vertical position of the heads, as disclosed in U.S. Pat. No. 5,530,607 (Spendlove). The wings are in close proximity to the heads to fully ensure that the motion of the wing corresponds to the motion of the heads. The wings ride on opposed ramps fixedly disposed in the drive as the head of the linear actuator moves toward and away from the disk.
U.S. Pat. No. 4,965,685 (Thompson et al.) discloses a head loading mechanism for use with a radial arm voice coil actuator. The radial arm actuator comprises a bifurcated actuator arm that has upper and lower suspension arms mounted at its distal end. Magnetic heads are mounted on the ends of the respective suspension arms. The head loading mechanism of Thompson et al. includes an elongate head load arm that is pivotally mounted within the disk drive. Ramped prongs are formed at the distal end of the head load arm. When the disk drive is not in use, the suspension arms are separated by, and rest upon, the ramped prongs. When a disk is inserted into the disk drive, the actuator arm moves toward the disk surface causing the suspension arms to move down the ramped prongs and onto the recording surfaces of the storage medium.
U.S. Pat. No. 4,683,506 (Toldi et al.) discloses a mechanism for separating a pair of opposing read/write heads during disk insertion and for subsequently bringing the heads together onto the surface of a storage medium. Like other prior art mechanisms, this mechanism is also mounted in the disk drive.
U.S. Pat. No. 5,638,241 (Sonderegger) discloses a disk cartridge comprising a disk-shaped storage medium and an outer casing that houses the storage medium. The outer casing has a head access opening for providing access by the read/write heads of a disk drive to the disk-shaped storage medium within the casing. Head loading/unloading ramps are provided in the cartridge proximate the head access opening for loading and unloading the read/write heads of the disk drive to and from the storage medium. The head loading/unloading ramps comprise first opposed ramps that separate the read/write heads as they approach the storage medium within the casing, and second opposed ramps that bring the heads together for loading onto the storage medium in a controlled manner. Placement of the ramps within the cartridge allows the movement of the read/write heads to be more accurately controlled in relation to the vertical position of the storage medium.
However, these traditional ramping methods of carrying the suspension onto and off of the surface of the data storage medium tend to tilt the suspension in roll. In addition, torque is applied to the slider during the lifting and loading process due to the fact that traditional suspensions make contact with the ramp sliding surface. This roll of the suspension creates the potential of the heads damaging the surface of the storage medium. Traditional suspensions also twist as they travel on the ramp and scrap along the surface of the ramp. This scraping of the suspensions along the ramp surface results in scraping debris that may affect the operation and performance of the disk drive. Mechanical clearances are also very tight in this area of the disk drive and disk. These traditional ramp-type lifting devices accomplish the head lifting process by means of the suspension sliding on a ramp surface. This requires that the ramps be located in close proximity to the heads at the end of the suspensions where tolerances are already very tight. This results in tight mechanical tolerances in these traditional configurations.
The present invention is directed to a method and apparatus for roll stabilized head lifting for improving the loading and unloading of read/write heads onto a surface of a data storage medium for data recording/reading, wherein a lifter device uses a sliding shelf to reduce roll during the load/unload operation. The apparatus of the present invention lifts the suspension from below such that roll is not introduced at the air bearing of the recording head, thereby reducing the chance of disk damage during head loading and unloading operations.
According to one aspect of the present invention, a head lifter device is disclosed for lifting the read/write head of a disk drive into and out of engagement with a data storage medium of a disk comprising a ramp structure disposed proximate the peripheral of the data storage disk and a carriage assembly in sliding contact with the ramp structure. The carriage assembly has a sliding shelf portion that lifts the read/write head in such a manner so as to minimize roll as it lifts the suspension. This is accomplished by maintaining a plane defined by the flat shelf section substantially parallel to a plane defined by the surface of the disk.
The flat shelf section of the sliding shelf portion carries the heads into and out of engagement with the surface of disk. The suspensions are lifted from the disk from below by the flat shelves such that there is substantially no roll at the interface of the heads and the surface of disk and no rubbing action between flat shelves and suspensions. The flat shelves are carried up lifting ramps to create a lifting process that produces approximately no twist on the suspensions. This results in nominally zero roll torque applied to the head sliders during the lifting and loading processes.
In accordance with a further aspect of the invention, the head lifter device further comprises a pair of opposed sliding shelf portions disposed on opposite sides of the disk, each of the sliding shelf portions lifts a corresponding head from engagement with opposing surfaces of the disk while maintaining a plane defined by the flat shelf section substantially parallel to a plane defined by the surface of the disk.
In accordance with a further aspect of the invention, each of the sliding shelf portions further comprises a flat shelf section proximate a first end of the sliding shelf portion, at least one pin proximate a second end, and a sliding body section that are disposed between and connects the flat shelf section to the pin.
In accordance with a further aspect of the invention, a means of positioning the sliding shelf portions in sliding contact with the ramp structure comprises at least one spring disposed between and connecting each of the opposed sliding shelf portions. The spring is coupled to at least one hole in each of the sliding body sections, and the spring acts to position the identical sliding shelves oriented in opposite directions in sliding contact with the ramp structure. The spring also acts to lower the sliding shelf portions down the ramp structure.
In accordance with a further aspect of the invention, the ramp structure further comprises an inverted L-shaped body having a support leg and a ramp leg. A sliding shelf ramp is disposed on the ramp leg and the sliding shelf ramp is in sliding contact with the sliding shelf portion. A closer pin ramp is disposed on the ramp leg and the closer pin ramp is in sliding contact with the pin of the sliding shelf portion. In a preferred embodiment, the closer pin ramp is substantially coplanar to the sliding shelf ramp. The ramp structure preferably further comprises a pair of opposing sliding shelf ramps and a pair of opposing closer pin ramps.
In accordance with a further aspect of the invention, the sliding shelf portion further comprises a recess that engages a stop disposed at the bottom of the lifting ramp to limit the travel of the sliding shelf potion in a direction toward the bottom of the lifting ramp.
In a further embodiment within the scope of the present invention, a system for lifting a read/write head of a disk drive onto or off of a disk medium is disclosed. The system includes a disk drive enclosure, an actuator disposed in the disk drive having an actuator arm, a suspension coupled to the actuator arm, a read/write head coupled to the suspension, and a head lifter device including a carriage assembly and a ramp structure. The carriage assembly acts to lift the suspension of the drive while maintaining a plane defined by the flat shelf section substantially parallel to a plane defined by the surface of the disk. In this manner, the suspensions are lifted from below by the flat shelf section in a direction having a vertical component that is substantially perpendicular to the surface of the disk. The carriage assembly slides on the ramp structure thereby lifting the read/write head into or out of engagement with the disk medium with substantially no roll.
In a further embodiment within the scope of the present invention, a method for lifting read/write heads of a disk drive into or out of engagement with a data storage medium is disclosed, comprising the steps of: providing a disk drive actuator disposed in the disk drive having an actuator arm, a suspension coupled to the actuator arm, and a read/write head coupled to the suspension; coupling a ramp structure to the inside floor of the disk drive enclosure; placing a carriage assembly in sliding contact with the ramp structure; lifting the suspension on the actuator with the carriage assembly while maintaining a plane defined by the flat shelf section substantially parallel to a plane defined by the surface of the disk; sliding the carriage assembly up the ramp thereby moving the read/write head away from a disk surface, or alternatively, sliding the carriage assembly down the ramp thereby moving the read/write head toward the disk surface.
In a further embodiment within the scope of the present invention, the lifter lifts the suspension from below in order to reduce the scrapping action of the suspension as it travels over the ramp surface. This help keep particulate debris off the head/gimbal assembly and improves performance and reliability. The use of this lifter device also allows the use of lift suspensions which would normally not work well with a traditional ramp loader.
In a further embodiment within the scope of the present invention, an improved lifting device lifts the read/write heads of the drive onto the disk medium, wherein the lifter device is placed partly up the suspension away form the head slider, between the actuator arm and the head slider. This improves the mechanical clearances within the disk drive.